Electronics & Music Maker - Oct 1983 Calrec 600 Series Microphones

Calrec 600 Series Microphone...

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Calrec 600 Series Microphones

Calrec CM656D.

Here is a unique UK made set of three cardioid capacitor mics, specially produced with the enthusiast in mind but with a full professional pedigree. Nowadays, the 600 series use the same capsules as the other ranges of Calrec capacitor mics. These are the 1000, 2000 and 2100 series which are used by the BBC and other UK organisations for TV applications.

The 600 series is offered as a low cost way of getting 'proper' capacitor mics (i.e. non electret) into the hands of enthusiasts. How are the costs reduced? First the powering is simplified with 50V DC being required, and the mic receives this on one wire of its lead with the signal being fed down the other, unbalanced. Both use the screen as return or common. The other ranges have the usual phantom powering, with various voltages catered for.

This alone doesn't account for the cost differences, but actually there isn't really any other reason nowadays. Originally the 600 series was a way of using up capsule production that was just outside specification for the other ranges, but now there has been a significant improvement in performance, particularly in high frequency smoothness. Also, the consistency of manufacture has improved so much that there are now no capsules outside tolerances, so the 600 series get the regular capsule production.

Common Features

The three mics in the 600 series all have 3-pin locking DIN connectors, hence the 'D' suffix. These are perfectly reliable and as each mic in a collection has to have a lead it doesn't really matter if the 'standard' XLR cannot be used. The idea seems to be to reduce the chance of inadvertently connecting XLR-fitted mics to the unbalanced 50V feed that these Calrecs need. Normally, putting a moving coil mic on a phantom fed XLR lead would not matter as no current can flow through the coil. In theory, this could be a problem with the 600 series arrangement but as I have done it with an AKG D202 with no ill effects, perhaps there is no real fear.

Calrec have a mains power supply unit for the 600 series called the CP622A. An address is given at the end of this review for one of the 600 series suppliers who has a free DIY circuit and other hints to enable further cost saving in the acquisition of capacitor mics.

The mics in this range are very robust and have handling noises below average. 'P' blasting is worse than average but this is only to be expected from a mic designed to respond to the ultimate subtleties of sounds.

As mentioned earlier, the signal feed is unbalanced. Most enthusiasts probably have unbalanced inputs on their recorders so this eases the connection aspect. Although balanced feeds would normally be considered necessary for long leads, the 600 series, with its high electrical output (much higher than moving coils or electret capacitors) is certainly not prone to hum pickup when used with long leads. Apart from the high output, the mics' source impedance is low and this also assists. They are intended to be used with inputs suiting 200 ohms or higher impedance mics.

The Calrec CP622A power unit has level controlling preset potentiometers to allow trimming of levels at the recorder/mixer end. The same idea can easily be incorporated in any DIY PSU, whether mains or battery. See postscript at the end of the review.

CM652D Cardioid

Calrec CM652D.

These are flat frequency response cardioid stick mics which offer very smooth high frequency portrayal and a 'natural' sound pickup. If you want a crossed stereo pair for high class choral, orchestral, brass band or similar recording then the CM652s meet this requirement. I have also used them regularly as overhead mics on drum kits, acoustic guitar pickups and for miking guitar amplifier cabinets. Seeing as the bass end of the mic is full and many rooms are boomy, the employment of some low frequency roll-off will be necessary to clean up the sound, leaving you with the superior transient attack of a capacitor mic.

This class of mic offers low colouration and consequently its results are best heard on better-class low colouration speaker systems. The cardioid pickup pattern is well maintained at high frequencies and this itself reduces colourations.

CM654D and CM656D Cardioids

Calrec CM654D.

These are both response-tailored vocal mics. The bass is inherently rolled off and there is a presence peak, and significantly this is higher up the range than is typical with moving coils. The low frequency roll off compensates for the proximity effect when the mic is used close up to the sound source, and the characteristic high frequency lift always strikes me as giving an immediate clarity without harshness, avoiding the muddiness which I feel characterises most moving coil vocal mics.

The CM654D can be used on acoustic guitar to good effect, particularly for sound projection as the high frequency boost brings out the plucked string sound.

The foam 'P' blast shield supplied is not totally effective if the mic is used with enthusiastic singers. I find that a subsidiary acoustically transparent screen a few centimetres in front of the Calrec's foam eliminates this nuisance: I use a couple of metal tea strainers with ladies' tights material between the meshes.

The CM656D is to all intents and purposes the same as the CM654D, with the addition of a strong wire mesh over the foam shield.